If is often difficult to determine a benign from a malignant stricture in the biliary and/or pancreatic ductal systems, as well as in the urinary tract. Endoscopic retrograde cholangiopancreatography (ERCP) or transhepatic cholangiography (THC) in the biliary tree and retrograde cystography in the urinary tract are helpful in determining abnormalities, however, it is difficult to discern benign inflammatory conditions from malignancies using these methods. Because it is important that a clear distinction be made, a definitive diagnosis ultimately requires sampling of tissue from the stricture.
A variety of procedures may be used for tissue sample acquisition. These techniques include percutaneous needle aspiration under CAT (Computerized Axial Tomography) or ultrasound guidance, T-tube aspiration of bile or pancreatic juice, percutaneous transhepatic or transpapillary catheter aspiration during ERCP, transhepatic or transpapillary scrape biopsy, and percutaneous biopsy using a biopsy gun. Some of these techniques are time consuming and/or tedious, and further, the diagnostic yield is poor.
Brush cytology has been shown to reliably diagnose a malignant stricture with a sensitivity of about fifty percent. However, standard brush cytology is often difficult or impossible to perform.
One of the known brushing techniques for biliary or pancreatic strictures involves placing a guide-wire across the stricture in question. Usually, the guide-wire is already in position following ERCP. A catheter or sheath is then fed along the guide-wire and into position at the proximal end of the stricture. The guide-wire is then removed from the catheter and the cytology brush is then inserted into the catheter and advanced to the site of the stricture. Once the brush exits the distal end of the catheter, brushing of the suspect lesion can be performed by repetitive push/pull manipulation of the proximal end of the brush. The brush is then withdrawn from the catheter and the guide-wire re-inserted.
This known brushing method suffers from several shortcomings. First, withdrawal of the brush through the catheter results in some, if not most of the sample being lost along the surface of the catheter during the withdrawal. Secondly, removal and re-insertion of the guide-wire is a tedious and time consuming process. Further, re-insertion of the guide-wire may be impossible due to tissue swelling and, as a result, access to the biliary or pancreatic duct may be lost.
If brushing could be performed without removal of the guide-wire, cytologic sampling could be performed more swiftly, accurately, and without the risk of losing access to the duct above the stricture.